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View Full Version : I vote for today's APOD (3/27) as Picture of the year!



John Kierein
2003-Mar-27, 09:23 AM
Wow.
http://antwrp.gsfc.nasa.gov/apod/astropix.html
More here:
http://space.com/scienceastronomy/light_echo_030326.html

DStahl
2003-Mar-27, 11:15 AM
WOW! WOW!

Here's another link, available also in the APOD caption: Hubble site (http://hubblesite.org/newscenter/archive/2003/10/image/a)

Thanks, John!

gethen
2003-Mar-27, 01:15 PM
Beautiful!! Also thught the "animation" made up of a series of photos was amazing.

Glom
2003-Mar-27, 01:43 PM
My friend Xandy says it is a drawing because stars don't actually have those plus signs on them. Can some actual astronomy experts set him straight, please?

As for my thoughts, that is one brilliant photo.

AstroCreep
2003-Mar-27, 01:49 PM
From what I understand, the X's in the stars are caused by the mounts inside the telescope. edit to include the quote.
here's a quote from this page:

http://www.wncc.net/courses/aveh/lecture/lec_astro_photography.htm

"Both pictures were taken with the HST (showing parts of the Orion Nebula and of the globular cluster M33). Notice that the bright (over-exposed!) stars exhibit four major diagonal spokes and four fainter ones in between: HST's mirror needs to be mounted and apparently it has four major and four minor stress points/lines due to mounting, and these "warp" the mirror enough so that these stress points show up as star spokes on long exposures. PS the purplish stars in the Orion shot also exhibit Airy disks. These are explained in my Hubble lecture. "

nebularain
2003-Mar-27, 04:30 PM
I found this interesting:

"Its outburst discovered in January 2002, observations have indicated that V838 Mon somehow transformed itself over a period of months from a small under-luminous star a little hotter than the Sun, to a highly-luminous, cool supergiant star -- defying the conventional understanding of erupting stars and stellar life cycles." (emphasis mine)

Kewl!!

Chip
2003-Mar-27, 05:59 PM
Wow.


I found this interesting too. (From picture's description.)

"But the nebula is actually a series of light echoes from formerly unseen shells of dust up to light-years in diameter. Previously ejected, the intricate shells progressively reflect light as it reaches them from V838 Mon's outbursts. Astronomers anticipate that light echoes from farther out in the dust envelope will continue to be visible until about 2010."

"Light echos" - cool. Would someone care to explain that in more detail? :wink:

Kaptain K
2003-Mar-27, 06:31 PM
My friend Xandy says it is a drawing because stars don't actually have those plus signs on them. Can some actual astronomy experts set him straight, please?

As for my thoughts, that is one brilliant photo.

Those "plus signs" are diffraction spikes caused by the supports for the secondary mirror. Any reflector (except Schmidt-Cassegrains and Maksutov types which attach the secondary to a clear corrector plate or lens) will show these spikes. Four supports give four spikes. Three supports cause six spikes. 8)

Glom
2003-Mar-27, 06:55 PM
I new saturation was something to do with it. Why it took the form of plusses, I was sure until now. I'll show him this post tomorrow.

Tom
2003-Mar-27, 07:08 PM
"Light echos" - cool. Would someone care to explain that in more detail? :wink:

Actually reflections. What is interesting is that we can observe the reflections as they travel through the dust clouds... These are reflections from the main "burst", and are propagating at light speed! Expect to see the "trailing edge" in the center area with further observations.

This is an extremely accurate way to measure the size of the clouds, BTW.

John Kierein
2003-Mar-28, 08:19 AM
I would think that knowing the the exact size from the light speed would allow a trigonometric measure of the distance. The APOD says that the 20,000 lt years is just an estimate, but I'll bet that they can do better than that now??

beskeptical
2003-Mar-28, 10:40 PM
I would think that knowing the the exact size from the light speed would allow a trigonometric measure of the distance. The APOD says that the 20,000 lt years is just an estimate, but I'll bet that they can do better than that now??

Go for it John. I'd love to know if it confirms or refutes your red-shift hypothesis.

nebularain
2003-Mar-28, 11:39 PM
Hey, John - Your link to the APOD page opened up to today's (March 28) APOD. Do you think you can fix that? Thanks!

Kaptain K
2003-Mar-29, 02:45 AM
nebularain,
At the bottom of the page, just click on the back arrow at the left side of the row (next to "Archive")

tracer
2003-Mar-29, 03:37 AM
Wow! I had no idea they had cameras in 1006 A.D.! ;)

David Hall
2003-Mar-29, 11:52 AM
Here's a direct link to the APOD page.

http://antwrp.gsfc.nasa.gov/apod/ap030327.html

(Let this be a warning to everyone. You need to get the archived page and not the daily page. 8) )